页岩地层取心技术研究及现场应用

Coring Techniques in Shale Formations and Their Field Application

  • 摘要: 针对页岩地层取心钻进时存在的机械钻速慢,岩心易破碎,易堵心、卡心,取心收获率偏低,出心作业时岩心容易从层理处破裂而影响后期分析等问题,采用高强度低摩阻铝合金内筒代替钢制内筒,配套岩心吊装转移装置进行地面转移,研发了新型耐磨抗冲击取心钻头,建立了取心工具稳定性分析模型,根据理论计算结果优选了取心钻具组合和施工工艺参数,初步形成了页岩地层取心配套技术。该取心技术已现场应用12井次,机械钻速提高1倍以上,单筒进尺提高50%,出心时间缩短为20~30 min,典型区块的取心收获率达到95%以上。现场应用表明,该取心技术可以满足页岩地层取心要求,能显著提高取心效率及取心收获率。

     

    Abstract: During coring in shale formations, the ROP (rate of penetration) is normally low, and core breakage, plugging and sticking occur frequently and the core recovery rate is low. In addition, they tend to fracture at bedding planes when being taken out of the core barrels. Therefore, the subsequent core analysis is impacted adversely. In order to deal with these difficulties, the original steel inner core barrels were replaced with high-strength low-friction aluminum alloy ones, and core lifting and transferring tools were transferred to the surface. New wear-proof and impact-resistant coring bits were developed too. A model was built to analyze the stability of coring tools. Finally, coring tool assembly and parameters were optimized on the basis of theoretical calculation results. When all these techniques were applied comprehensively on well site, ROP increased by 100%, single-barrel footage increased by 50%, core handling time reduced to 20-30 minutes, and the core recovery rate of typical blocks achieved over 95%. It indicated that new coring techniques can meet the requirements of coring in shale formations and considerably improve coring efficiency and recovery rate.

     

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